The present invention relates in general to an improved tool and corresponding improved methodology for brake maintenance, and in particular to improved maintenance operations for drum brake arrangements.
A conventional vehicle wheel drive assembly has a brake arrangement operatively configured for selectively slowing and/or stopping rotation of a wheel associated therewith. In a typical arrangement, an exposed wheel flange constitutes a wheel mounting member which is directly connected to either a driven or free turning axle, depending on the drive train arrangement of a particular vehicle and the location of the vehicle wheel drive assembly. The exposed wheel flange typically may include a central hub projecting in an axial direction from the face of the exposed flange. Threaded bolt elements also may project from the exposed flange for direct receipt of openings defined in a corresponding wheel rim, with the wheel then being secured to the wheel mounting member by threaded nuts.
The foregoing arrangement takes up a finite and substantial amount of room in a given wheel drive assembly. Also within the confines of such an assembly is the above-referenced braking mechanism.
One conventional arrangement is referred to as a drum brake arrangement. A drum brake arrangement makes use of two curved brake shoes, which are typically fitted with heat and/or wear resistant linings. Braking operations are achieved by forcing the two curved shoes against the surface of a rotating drum.
Typically, the brake shoes are held into a null or predetermined initial position (during ceased braking operations) by respective brake springs. Such brake springs may comprise resilient cantilevered elements, such as in the case of drum brake arrangements for rear vehicle wheel drive assemblies for General Motors automobiles from 1992 through 1997.
Still other elements are present in typical existing drum brake arrangements, such as a coiled spring for brake self-adjustment, and a brake adjustment element which can be manually set.
In general, maintenance operations concerning such conventional drum brake arrangements are widely known and long standing. For example, heat and/or wear resistant linings of the conventional brake shoes naturally wear out over time and must be inspected and/or replaced. Other functional elements of the conventional drum brake arrangement should also be periodically inspected and/or maintained, as well known to those of ordinary skill in the art.
Routine drum brake maintenance operations typically involve disassembly and re-assembly of the arrangement. With the vehicle wheel dismounted from the wheel mounting member, the wheel flange is exposed for a vehicle technician to perform drum brake maintenance. Typically, the technician must find a way to relieve the spring loading forces which are applied by the respective brake springs to the respective brake shoes. Since the brake shoes are held in place by the springs and cannot be fully inspected and/or maintained until removed, the holding force of the springs must be released for drum brake maintenance operations to take place.
In addition to relieving such spring-loading force, the technician must find a way to hold the released cantilevered brake spring in a restrained position while the brake shoes are removed and/or reinserted. Alternatively, old brake shoes are removed and new brake shoes or old brake shoes with new linings are repositioned during the course of brake maintenance.
Typical technician operations have often times simply involved a "brute force" approach, utilizing pliers and/or screwdrivers for prying and holding a cantilevered brake spring from a respective brake shoe. Such approach generally has only mixed success, is time consuming, is potentially dangerous to the technician or other bystanders, and addresses only one brake shoe at a time.
The above conventional methodology is also unreliable in the sense of the "trial and error" approach which must be taken in efforts to grasp, remove, and hold the cantilevered brake spring. The difficulty factor is also raised due to the fact that the technician is attempting to operate against the force of the spring, at the same time that they need to use their hands to physically dislodge and/or remove the brake shoe once released from the force of the brake spring.
The net result is a time consuming, unsatisfactory aspect of typical drum brake maintenance operations.
Several companies make specialized forms of pliers, comprising basically enlarged tongs, some more than a foot long. Specifically, they generally comprise X-shaped scissor action specialized pliers, with a hook and/or notches on either end. Generally speaking, while providing an ability for prying a brake shoe retaining spring away from the brake shoe, the device still does not provide for holding the retaining spring in a released position for ease of brake shoe removal and replacement. Also, they do not provide for simultaneous operations with two released and held brake springs, nor do they facilitate re-engagement of springs to shoes. See, for example, Part No. 3365 "Brake Spring Pliers" manufactured for NAPA Distribution Centers by Danaher Tool Group, Lancaster, Pennsylvania, and Part No. J 38400 "Brake Shoe Spanner & Spring Remover" by the Kent-Moore Company. Such GM brake shoe spanner and spring remover product available in the marketplace comprises a similar X-shaped scissoraction device more than a foot long. It is marketed through Kent-Moore company, originating as Part No. J 38400 by OTC, a division of SPX Corporation of Owatonna, Minn. 55060-1171.